The Macronutrient Series: All About Carbohydrates

Carbohydrates (also known as carbs) are one of the three macronutrients that we need to live well and function optimally; in fact, they are our body’s primary source of energy (calories)! Carbohydrates can be categorized as sugars, starches or fibre – and can be further classified as simple or complex. Regardless of what a carbohydrate is labelled as, all carbs end up being broken down into glucose (sugar) molecules during the digestive process.

When we eat carbohydrates (such as a bagel, fruit, or granola bar), it is broken down into glucose and released into the blood stream. When these sugars are released into the blood stream they can now be transported for use as energy throughout the body. Interestingly, the chemical composition of the food we eat will determine how quickly it breaks down into glucose and how quickly it can be utilized as energy in the body.

Simple carbohydrates are quickly broken down by the body and utilized as a fast source of energy. The quick absorption of simple carbohydrates causes a very short spike in blood sugar levels followed by a crash (drop in blood sugar levels). It’s important to note that some simple carbohydrates are better for you than others. For example, items with added refined sugar such as white sugar, brown sugar, chocolate bars, donuts, and desserts, tend to be highly processed and contain poor nutritional content. The highly processed refined sugar in these items leads to a burst of energy followed by a quick drop in energy resulting in fatigue, hunger, and cravings for more sugar shortly after consumption. They can also lead to poor portion control and overindulgence. However, there are some healthier simple carbohydrates we should include in our diet such as fruit and milk products. Fruit and milk products have naturally occurring sugar and often contain some vitamins, minerals, and fibre that our bodies need!

Complex carbohydrates are a more sustainable source of fuel as they usually contain a substantial amount of fibre, vitamins, and minerals. They are made of complex sugar molecule chains, so they take much longer to digest and breakdown in the body. Due to the slower digestion time of complex carbohydrates, our blood sugar levels are not affected as dramatically as they are with simple carbohydrates. Energy from complex carbs is released slowly and in a more gradual manner, which provides us with energy for a longer period of time and without experiencing that ‘crashing’ feeling.

As you can see, it’s important to include more complex carbohydrates in your diet and limit your intake of the highly processed simple carbohydrate foods.

When should I eat simple carbs versus complex?

Simple Carbs: As mentioned previously, simple carbohydrates will provide you with a quick burst of energy (spike in blood sugar). When you want to go for a short run or short workout, try to consume a healthy source of simple carbs beforehand, such as a banana for a fast source of energy. Fruit will give you additional nutrients and vitamins & the sugar is naturally occurring. 

Complex Carbs: If you’re going out for a long hike, 45-minute bike ride, or just want to stay satiated until lunch during your workday, you will want to start your day with a complex carbohydrate source such as, a bowl of oatmeal with bananas. Complex carbs will sustain your energy levels much longer due to the gradual rise in blood sugar, fibre content, & slow energy release time.

Check out the table below for examples of simple and complex carbohydrates:

Examples of Simple Carbohydrates:  Examples of Complex Carbohydrates:
White refined baked goods (i.e. bread, crackers, buns)
Sugars: white, brown, etc.
Juice & Pop
Fruit (naturally occurring sugar)
Milk (naturally occurring sugar)  
Whole grains: oats, quinoa, barely, brown rice, whole grain pastas and breads

Legumes: black beans, kidney beans, lentils, chickpeas

Starchy Vegetables: potatoes, sweet potatoes, corn

Fibre rich fruits and vegetables: sweet potato, broccoli, green beans, kale, carrots, asparagus, apples, dates, blackberries etc.  

Prioritizing complex carbohydrates and minimizing simple carbohydrates is essential to keep our blood sugar levels stable and in a healthy range! Here are some easy ways you can incorporate more complex carbohydrates into your diet:

  1. Load up half of your dinner plate with colourful vegetables and one quarter of your plate with complex carbohydrates
  2. Swap your white-refined baked goods, pasta, rice & crackers, for whole grain options (e.g. quinoa, brown rice, or whole grain spaghetti).
  3. Grab a handful of fruit rather than a handful of chocolate, cookies, or candy for added vitamins, minerals, and fibre.
  4. Add beans and legumes to your salads, chilis, and pasta sauces.
  5. Try out some new recipes that you can prepare in advance and enjoy as a convenient snack such as granola bars, whole-grain muffins, or whole wheat banana bread.

If you are interested in learning more or would like to speak with a Dietitian regarding your nutrition habits, click here to find a Dietitian near you:


Boston, 677 Huntington Avenue, & Ma 02115 +1495‑1000. (2012, September 18). Carbohydrates. The Nutrition Source.

Carbohydrates: Types & Health Benefits. (n.d.). Cleveland Clinic. Retrieved March 20, 2022, from



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